“Realist” critical views on international law discount the idea that external norms determine the behavior and objectives of states. However, they risk replicating the very positions they criticize as a result of two common errors. First, they frequently assume that legal norms have clear and uncontested meanings that all observers will agree upon. Second, they assume the preexistence of the state as a rational, self-interested actor. The uncertain content of norms, and the uncertainty and fragility of the state’s stability, power, and rationality thus go unrecognized.

This Article proposes an agenda for further International Legal Realist theory premised on pragmatic analysis of the concept of state sovereignty. To this end, it develops the thought of the legal and political philosopher Carl Schmitt, arguably the most thorough and influential Realist critic of modern international law. For Schmitt, drawing on Thomas Hobbes, the sovereign power of the state is itself justified by the essential epistemic uncertainty of all disputes over norms and values. Only conscious institution of the sovereign authority could solve the conflict resulting when there is no agreement as to “who decides” how to define and apply contested norms — as is still the case today in many disputes among states.

Reemphasizing this centrality of epistemic uncertainty to the institution of sovereignty helps to set a new agenda for Realist international law theory. Neither states nor international norms and their interpreters should be taken as unproblematic elements of a unified order: rather both are heuristic tools that can be evaluated on the basis of their utility in procuring certain judgments on normative conflicts. From the North Korean nuclear weapons issue to the UK’s Brexit decision, this approach can potentially help legal scholars and practitioners to make more accurate determinations of the stakes and possible outcomes of many of today’s most pressing international legal disputes—and even help in conceiving alternatives to the current status quo.